Generator geht nicht

package com.example.writesave;


import androidx.appcompat.app.AppCompatActivity;


import android.os.Bundle;
import android.widget.Button;
import android.widget.TextView;


import java.util.Random;


public class NewKey extends AppCompatActivity {


    private Button bntSave;
    private TextView yourKey;


    private String[] allKeys  = {"°", "!","§","$","%","&","/","(",")","=","?","@","€","*","+","~","'","#","<",">","|",";",",",":",".","_","-","a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z","ß","1","2","3","4","5","6","7","8","9","0"};
    private String[] key;
    private String set;
    private String[] used={"´","´","´","´","´","´","´","´","´","´","´","´","´","´","´","´","´","´","´","´","´","´","´","´","´","´","´","´","´","´","´","´","´","´","´","´","´","´","´","´","´","´","´","´","´","´","´","´","´","´","´","´","´","´","´","´","´","´","´","´","´","´","´","´"};
    private boolean go;
    private boolean isKeyFree;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_new_key);
        getSupportActionBar().hide();
        key = new String[64];
        go = false;
        isKeyFree = true;
        Random random= new Random();
        for(int i = 0; i <= allKeys.length; i++){
            while (go == false){
                int thisKey = random.nextInt(allKeys.length);
                isKeyFree = true;
                for(int j=0;j<=used.length;j++){
                    if(allKeys[thisKey] == used[j]){
                        isKeyFree = false;
                        break;
                    }
                }
                if (isKeyFree = true){
                    used[i] = allKeys[thisKey];
                    set = set + allKeys[thisKey];
                    go = true;
                }
            }
        }
        yourKey.setText(set);
    }
}