Is there a way to make my program's logic without a lot of case statements? [closed]

I'm making a program that creates random trades, but there's a lot of conditional statements to prevent duplicate or pointless trades (ex: trading items A and B for B and A, or trading A and B for C and A, etc.)

Is a ton of if-else statements the best approach, or is there a more effective method to process conditions and give correct outputs?

Here's some older code I used to use prior to starting again on this project from scratch:

        int[] prevTrade = new int[5];
        //  Note previous trade info
        prevTrade[0] = this.tradeSlot1;
        prevTrade[1] = this.tradeSlot2;
        prevTrade[2] = this.tradeSlot3;
        prevTrade[3] = this.tradeSlot4;

        //  Reset trade choices
        this.tradeSlot1 = -1;
        this.tradeSlot2 = -1;
        this.tradeSlot3 = -1;
        this.tradeSlot4 = -1;

        // Generate output list for conversion to image
        int[] outList = new int[5];

        //  Make trade small or large using random number
        int randTradeSize = (int)(Math.random() * 100);
        //java.awt.Toolkit.getDefaultToolkit().beep();

        if (randTradeSize >= 75) {  // is a 2 for 2 trade, happens 25% of the time
            this.tradeSize = "Large";
            //  Create a new trade offer with 4 outputs (2 items for 2 other items)
            while (randTradeSize != -1) {
                this.tradeSlot1 = newTrade();
                this.tradeSlot2 = newTrade();
                this.tradeSlot3 = newTrade();
                this.tradeSlot4 = newTrade();

                if (((this.tradeSlot1 == this.tradeSlot3) && (this.tradeSlot1 == this.tradeSlot4) && (this.tradeSlot2 == this.tradeSlot3) && (this.tradeSlot2 == this.tradeSlot4)) || (this.tradeSlot1 == this.tradeSlot3) || (this.tradeSlot1 == this.tradeSlot4) || (this.tradeSlot2 == this.tradeSlot3) || (this.tradeSlot2 == this.tradeSlot4) || ((input.tradeSize == "Large") && (secondTrade.tradeSize == "Large")) && ((input.tradeSlot1 == secondTrade.tradeSlot1) && (input.tradeSlot2 == secondTrade.tradeSlot2) && (input.tradeSlot3 == secondTrade.tradeSlot3) && (input.tradeSlot4 == secondTrade.tradeSlot4)) || ((input.tradeSlot1 == secondTrade.tradeSlot1) && (input.tradeSlot2 == secondTrade.tradeSlot2) && (input.tradeSlot3 == secondTrade.tradeSlot4) && (input.tradeSlot4 == secondTrade.tradeSlot3)) || ((input.tradeSlot1 == secondTrade.tradeSlot2) && (input.tradeSlot2 == secondTrade.tradeSlot1) && (input.tradeSlot3 == secondTrade.tradeSlot3) && (input.tradeSlot4 == secondTrade.tradeSlot4)) || ((input.tradeSlot1 == secondTrade.tradeSlot1) && (input.tradeSlot2 == secondTrade.tradeSlot2) && (input.tradeSlot4 == secondTrade.tradeSlot3) && (input.tradeSlot3 == secondTrade.tradeSlot4)) || ((input.tradeSlot2 == secondTrade.tradeSlot1) && (input.tradeSlot1 == secondTrade.tradeSlot2) && (input.tradeSlot3 == secondTrade.tradeSlot3) && (input.tradeSlot4 == secondTrade.tradeSlot4))) {
                    this.tradeSlot1 = -1;
                    //System.out.println("Large\tInvalid Trade");
                }

                if ((this.repeatTrade(this, prevTrade) == false) && (this.tradeSlot1 != -1)) {
                    randTradeSize = -1;
                    outList[0] = this.tradeSlot1;
                    outList[1] = this.tradeSlot2;
                    outList[2] = 5; //  arrow.png
                    outList[3] = this.tradeSlot3;
                    outList[4] = this.tradeSlot4;
                    //System.out.println("Large\tTrade Success");
                }
            }
        } else {        // is a 1 for 1 trade, happens 75% of the time
            this.tradeSize = "Small";
            //  Create a new trade offer with 2 outputs (1 item for another item)
            while (randTradeSize != -1) {
                this.tradeSlot1 = newTrade();
                this.tradeSlot2 = newTrade();
                this.tradeSlot3 = -1;
                this.tradeSlot4 = -1;

                //  Check if trade is copy of other trade
                if ((this.tradeSlot1 == this.tradeSlot2) || (((input.tradeSize == "Small") && (secondTrade.tradeSize == "Small")) && (input.tradeSlot1 == secondTrade.tradeSlot1) && (input.tradeSlot2 == secondTrade.tradeSlot2))) {
                    this.tradeSlot1 = -1;
                    //System.out.println("Small\tInvalid Trade");
                }

                //  Check if trade is repeat, then if all other parameters are met
                if ((this.repeatTrade(this, prevTrade) == false) && (this.tradeSlot1 != -1)) {
                    randTradeSize = -1;
                    outList[0] = this.tradeSlot1;
                    outList[1] = 5; //  arrow.png
                    outList[2] = this.tradeSlot2;
                    outList[3] = -1;    //  null value, no image
                    outList[4] = -1;    //  null value, no image
                    //System.out.println("Small\tTrade Success");
                }
            }
        }
        //  Reset random trade lifetime
        this.randTradeLifetime(this);
        return outList;
    }```